Chứng minh: $1.9999999999999…=2$ Đặt $A=1.99999999999…. \to 10A=19.999999999…..$ $B=2 \to 9B=18$ Ta có $19.999999999….=18+1.999999999…$ $\L
Chứng minh: $1.9999999999999…=2$ Đặt $A=1.99999999999…. \to 10A=19.999999999…..$ $B=2 \to 9B=18$ Ta có $19.999999999….=18+1.999999999…$ $\Leftrightarrow 10A=9B+B$ $\Leftrightarrow 10A=10B$ $\Leftrightarrow A=B$ $\Leftrightarrow 1.99999999999…=2$ Tìm lỗi sai chơi nào mọi người